全球变化下有关卤代甲烷源汇的研究进展

Advances of researches on source and sink of methyl halide under global changes

大气中存在的卤代甲烷对臭氧层具有极强的破坏作用并参与其它气候现象,其动态变化对臭氧的恢复和地球生态系统有重要影响。文章概述了全球变化下卤代甲烷源汇的研究情况并简单探索其进一步的研究方向。几种卤代甲烷中,溴代甲烷源汇最复杂且对臭氧具有最强的破坏力,因此研究较多。已证明CH3Br的来源有:海洋、土壤、生物燃烧、陆地植物和沼泽地的释放等;CH3Br的汇包括:光化学分解、被土壤和植物吸收、在海洋中的化学和生物降解等。但事实上是已知汇远远大于已知源,且各个源汇的通量在不同研究中结果差异较大,归其原因是卤代甲烷释放与吸收机制的不确定性。虽然近几年的研究也应用了稳定同位素示踪技术,但卤代甲烷各源汇的具体贡献并不清楚。今后卤代甲烷源汇的研究重点应放在与气体产生机制最密切的地下部分即“地下生态学”对其通量的影响,而同位素技术的改进及其在痕量气体研究中的应用也将是未来的重点方向。

Methyl halides in the atmosphere plays an important role in destroying the ozone layer and participating in other climate phenomenon. Its dynamic change affects greatly on the recovery of ozone and ecology system on the earth. This paper summarized the researches on source and sink of methyl halides under global change and explored the further study orientation. Among methyl halides, more researches on the source and sink of CH3Br have been taken because of its complex sources and stronger destroying potential. The known sources of CH3Br are oceanic production, fumigation of soils, biomass burning and terrestrial plants and marsh emission. And the known sinks include photochemical decomposition in the atmosphere, loss to soils and uptake by green plants, chemical and biological degradation in the ocean. In fact, identified sinks outweigh known sources and fluxes of each source and sink have great discrepancy in different results, this is due to uncertainty of gas production and degradation mechanism. Although the technology of stable isotope has been used in recent years, the contribution rate of each source and sink is not still clear. In the future, the main researches on methyl halides should focus on the effect of belowground ecology on the fluxes. And the improvement of the technology of stable isotope and its applying in trace gas study will be another emphasis.